1. Field of the Invention
The present invention relates to a measurement apparatus and a measurement method, and more particularly to a measurement apparatus and a measurement method which allow to accurately measure motion states of both an impacting object and an impacted object.
2. Description of the Related Art
In such sports as baseball, golf, tennis and soccer, it is important to measure the speed of an impacting object, such as a bat, golf club and tennis racket used by a player, or a leg of a soccer player, in order to measure the capability of a player in terms of power. It is also important to measure the speed of an impacted object, such as a baseball, golf ball, tennis ball and soccer ball, in order to measure the quality of the impact (shot) performed by a player, that is to measure the performance level.
Therefore it is a basic and important measurement to simultaneously measure the speed of an impacting object and that of an impacted object in sports, in order to improve the performance in a respective sport. Various methods have been used for these measurements, such as a method of using images, a method of using magnetism, a method of using an optical sensor, and a method of using a Doppler sensor; but the method of using a Doppler sensor, in particular, is frequently used lately, since it is simple and has low cost.
For example, the speed of a club head during swinging is measured in golf using a Doppler sensor (e.g. Japanese Patent Application Laid-Open No. 2006-326318). In some cases, both the speed of a club head (head speed) as an impacting object and the speed of a golf ball (ball speed) as an impacted object are measured in golf using a Doppler sensor (e.g. Japanese Patent Application Laid-Open No. 2010-025737).
However according to the measurement method disclosed in Japanese Patent Application Laid-Open No. 2010-025737, the speed of a club head and the speed of a golf ball are measured based on the Doppler signals obtained by one Doppler sensor. In this case, the critical issue is whether the Doppler signals obtained from one Doppler sensor can be appropriately separated into signals for the club head and signals for the golf ball, however accurate separation of signals is difficult if the speed of the club head and the speed of the golf ball are similar. This may make it difficult to accurately measure the motion states of the club head and the golf ball.